Along with the increasingly development of science and technology, digital devices such as mobile phone, personal digital assistant (PDA), notebook and such like, are developed to be more convenient, versatile and artistic. Display screens are indispensable man-machine communication interfaces in these digital devices. At present, most of the display screens use liquid crystal display (LCD) technology.
On the other hand, along with the rapid development and application of information technology, wireless communication and information appliance, in order to be easier, lighter and more user-friendly, many information products use touch panel as an input device instead of conventional input device such as a keyboard or a mouse, and now touch-sensitive LCD device has become a mainstream product.
The touch-sensitive LCD device mainly includes two types, one of the two types is named On Cell whose touch panel is directly attached on the LCD panel, and the other of the two types is named In Cell whose touch sensors are integrated into the LCD panel. However, thickness of a conventional On Cell touch-sensitive LCD device is too large, and due to complex structure and complex manufacturing process, production yield of the In Cell touch-sensitive LCD device is low. Therefore, one layer On Cell touch-sensitive LCD device is developed, which forms a single touch-sensitive layer having transparent electrode pattern between an upper substrate and an upper polarizer of the LCD panel. Comparing with the conventional On Cell touch-sensitive LCD device, one layer On Cell touch-sensitive LCD device at least omits one transparent substrate and one adhesive layer, therefore, the thickness of one layer On Cell touch-sensitive LCD device is smaller. Comparing with In Cell touch-sensitive LCD device, the manufacturing process of one layer On Cell touch-sensitive LCD device is simple, and the production yield of one layer On Cell touch-sensitive LCD device is high. Thus, one layer On Cell touch-sensitive LCD device is widely used.
Referring to FIG. 1, FIG. 1 is a schematic plan view of a typical one layer On Cell touch-sensitive LCD device. As show in FIG. 1, the touch display device 10 includes an upper substrate 11 and a lower substrate 12. A touch-sensitive layer (not shown) formed of transparent conductive material is disposed on the upper substrate 11. Sensitive electrode lines (not shown) of the touch-sensitive layer are connected to an external touch printed circuit board (PCB) (not shown) via a flexible PCB 13. Display electrode lines are disposed on the lower substrate 12, and are connected to a PCB 16 via a flexible PCB 15. A touch signal processing chip is disposed on the external touch PCB, and the flexible PCB 13 transfers touch-sensitive signals from the sensitive electrode lines to the external touch PCB for the touch signal processing chip to process. The PCB 16 is disposed with power supply circuit, timing controller, image signal generator and so on, and provides power supply signals, image signals, driving signals, control signals, timing signals and so on which are used to display images to display panel via the flexible PCB 15.
However, due to the sensitive electrode lines of the touch-sensitive layer needing the flexible PCB 13 to connect the external touch PCB, the cost used to obtain the flexible PCB 13 and the external touch PCB is increased. Further, when assembling modules of the touch display device 10, the flexible PCB 13 and the external touch PCB need to be fixed behind the display panel, which occupies more space and increases the thickness of the touch display device 10. Furthermore, the flexible PCB 13 needs to bypass the lower substrate 12 to connect the external touch PCB, therefore, length of the flexible PCB 13 needs to be large enough; and due to stress generated when the flexible PCB 13 bends being large, the flexible PCB 13 is liable to fall off, which easily causes abnormal touch result.
In addition, in another case, the external touch PCB is omitted, and the touch signal processing chip is directly disposed on the flexible PCB 13. However, although the cost of the external touch PCB is accordingly saved, the disposing of the touch signal processing chip on the flexible PCB 13 needs redesigning mould or mold for the flexible PCB 13, and the manufacturing cost of the flexible PCB 13 is increased.
What is needed, therefore, is an improved touch display device that can overcome the above-described problems.